On the trail of pollution in Lausanne

At the end of 2020, dioxins and furans were discovered in the soil of Lausanne’s Vallon neighborhood, leading a group of five researchers – Aurélie Berthet (Unisanté), Florian Breider (EPFL ENAC), Alexandre Elsig (EPFL CDH), Céline Mavrot (UNIL), and Fabien Moll-François (EPFL CDH, Unisanté) – to join forces to better understand how the incinerator operated, the composition of the pollution, and why the pollution had gone undetected until 2020.

This interdisciplinary project was made possible by the Collaborative Research on Science and Society (CROSS) Program, which is co-funded by EPFL’s College of Humanities (CDH) and the University of Lausanne (UNIL), and encourages collaboration between the researchers of the two schools. It was conducted in conjunction with neighborhood associations to answer the questions posed by people currently living in the contaminated areas.

How to reconstruct the history of an incinerator

"It's very difficult to know what happened in this incinerator, how emissions are evolving and, potentially, how the population is being exposed,” explains Florian Breider, an environmental chemist who directs the Central Environmental Laboratory at EPFL’s School of Architecture, Civil and Environmental Engineering (ENAC).

To better understand what happened, the team worked together to ‘time travel’ to the past by accessing municipal, cantonal, and federal archives, political debates on waste management, as well as numerous technical documents.

Through these methods, the researchers learned why the Vallon neighborhood was chosen as the site of the incinerator. Initially the ‘higher-end’ La Sallaz neighborhood was considered, but after resistance from those residents, the site in Vallon was chosen, as it was a working-class neighborhood that was already considered “degraded” by some. And as it was in a valley, the visible chimney wouldn’t stand out as much. History would later show that the Vallon's topographical situation posed problems for optimal smoke dispersion.

The researchers were able to trace not only how the incinerator's technology worked, but also how the typology of the waste burned evolved over time. This study has contributed to a better understanding of the pollution profile of dioxins and furans in soil.

"There is no single dioxin or furan compound, but a set of 210 congeners with varying structural characteristics and levels of toxicity. Prior to this research, knowledge of this historical pollution profile was lacking," explains Aurélie Berthet, toxicologist at Unisanté.

"We were able to find information in the archives on the nature and quantity of waste burned, as well as technical specifications on combustion temperature and the flue gas filtration systems that were successively installed," explains Fabien Moll-François, historian and sociologist of science at EPFL CDH and Unisanté. By learning how much paper and green waste, for example, were incinerated, and in what quantities, the researchers were able to assess the chemical composition of the waste and its impact on the environment.

Two ENAC master’s students in environmental engineering, Alexis de Aragao and Xiaocheng Zhang, also assisted in the research as part of their design projects. Using the data and records collected by the CROSS team, they found that in the early 1970s, the incinerator had been used beyond its capacity, meaning that sometimes more than 50% of the total waste burned stayed behind as residue, important information from an environmental and socio-historical point of view.

"The study also highlighted governance problems, such as the abandonment of another incinerator project, which would have reduced overcapacity at the Vallon incinerator. In the 1980s, management of the incinerator became more complex due to relations between the city, Canton, and Confederation. Despite several warnings about heavy metals as early as the 1970s and dioxins in the 1990s, the incinerator was not brought up to standard within the normal regulatory timeframe. The study shows the limits of silo governance: at cantonal and communal level, the dossier was in the hands of technical departments, such as that of infrastructure and the environment, or industrial services, which contributed to limiting the extent to which public health considerations were considered. The canton has significant competencies in terms of waste planning, management and monitoring pollution caused by incineration, which tends to put it in the position of judge and jury," points out UNIL political scientist Céline Mavrot.

An interdisciplinary approach

The rules to apply for CROSS funding specifically stipulate that the project must include researchers from EPFL and UNIL, one specialist in social sciences and humanities, and one specialist in life sciences, natural sciences, or engineering. This allows new connections and collaborations to be formed that might not have otherwise taken place. Therefore, the five researchers on this project each came with a different and complementary specialization: history of science and the environment, public health, political science, and environmental chemistry.

As a toxicologist working in the field of global and environmental health at Unisanté, Berthet was one of the researchers involved in defining health recommendations relating to dioxin contamination of Lausanne soil. The idea for the interdisciplinary project arose from discussions with historian Moll-François who had done his thesis on dioxin pollution caused by the Gilly-sur-Isère incinerator in France and wished to continue his research in Lausanne. The project was then prepared in conjunction with Mavrot, a specialist in public health controversies.

With the support of Breider and Alexandre Elsig, a historian at CDH, the team was able to combine everyone’s expertise to produce a truly interdisciplinary work, using tools and methods from environmental chemistry, public health, history, and political sociology to gather data on the specific nature of pollution and its impact.

"It's quite rare for disciplines to work hand in hand like this and collaborate from the outset,” says Elsig. “Usually, the research is done consecutively, whereas here we were doing the whole process as a team, allowing the historical archive data to be injected into the environmental chemistry work, and all the knowledge of environmental chemistry could guide the archive work as well.”

By bringing together their different disciplines and working collaboratively, the team was able to answer many important questions and developed an approach that can be applied in other cases.

Addressing local issues

The team also credits the CROSS program with their ability to undertake a local project, carried out directly with the people impacted.

"As CROSS projects are co-funded by EPFL and UNIL, it means we can tackle local issues,” says Breider. “We thought about applying for SNSF funding, but this type of funding is usually not geared toward local topics. So CROSS was an ideal funding tool for this type of project, and I don't know how we could have done this project without it."

After initial discussions with residents to define the issue, the team returned to present the results on March 27 to around 100 people living in the areas most affected by pollution. The audience was very engaged, sharing their experiences and asking questions, for example about the possibility of pollutants other than dioxins being present in the soil, and the amount of time needed for pollutants to disappear from the soil. There were also questions about how pollution monitoring was organized and why the dioxin contamination was discovered so late. The team was able to provide answers to these questions while gathering valuable information on the nuisances suffered by local residents.

Going forward, the team and the two ENAC students will submit a scientific paper on the mathematical model they have developed to assess past emissions of dioxins and furans from waste incineration plants. This work will also be presented by Breider at an international conference in Taiwan on micropollutants and ecological risks.

The researchers would like to continue their investigations. Initially, they wanted to include the period 2006-2020, but due to a six-month delay in accessing certain archives, they didn't have time to go beyond 2005, as CROSS projects are only funded for one year. They are still searching for funding for a new phase of the project.

"It's not always easy to get support for this kind of interdisciplinary collaboration between the humanities and the basic sciences,” says Moll-François. “Yet it is vital that this type of work can be conducted within an academic framework that guarantees the independence of the research. In this sense, CROSS offers an innovative solution for conducting independent research on a subject that combines scientific, societal and political issues”.